Well, perhaps Ridley could have an entirely different way of dominating in the air?
One way I imagine Ridley could be implemented is by basing him around what I call a "sky assault" style of gameplay. Similar to Jigglypuff, Ridley is very mobile in the air, with multiple jumps, good air speed, and probably gliding and maybe even hovering like Peach thrown into the mix. Basically, Ridley would be really good at moving about in the air. I figure that one of the better ways to represent Ridley would to make him focused on staying in the air as much as possible, and while there, barrage the opponent from the sky with a mixture of fireballs, long range tail attacks, and the like. So unlike Jigglypuff, who focuses more on fighting foes while they're in the air too, Ridley would be more about keeping his foe on the ground and utilizing his specials to continually assault them from the sky, similarly to how he fights in his games.
That's just a basic idea, but I think it could work. If nothing else it does show possible ways for Ridley to be implemented into the game.